[petsc-users] compilation of fortran program that uses petsc hangs

[Matthew Knepley]

This sounds like a CMake bug. Have you tried to compile it with a PETSc
makefile?

ex16f: ex1f.o
      ${FLINKER} -o $@ $^ ${PETSC_LIB}

include ${PETSC_DIR}/lib/petsc/conf/variables
include ${PETSC_DIR}/lib/petsc/conf/rules


  THanks,

     Matt

On Tue, Jul 7, 2026 at 5:01 AM Ruyter de Wildt, Martijn de via petsc-users <
petsc-users at mcs.anl.gov> wrote:

> Good morning,
>
> When I try to compile a fortran program that uses petsc, the make command
> hangs and I can only stop it by killing the make process. I could not find
> any information about this problem and hope that you can shed some light on
> it.
>
>
> I can reproduce the problem with one of the examples that is included in
> the PETSc installation. To do this, I used the following steps:
>
>    - export PETSC_DIR=[PETSC_INSTALL_DIR]
>    - export PETSC_ARCH=
>    - mkdir -p test_petsc/build
>    - cp
>    [PETSC_INSTALL_DIR]/share/petsc/examples/src/sys/tutorials/ex16f.F90
>    test_petsc
>    - cp [PETSC_INSTALL_DIR]/share/petsc/CMakeLists.txt test_petsc
>    - in CMakeLists.txt, I replaced all ‘ex1’ with ’ex16f’ and all ‘.c’
>    with ‘F.90’.
>    - cd test_petsc/build
>    - cmake ..
>    - make VERBOSE=1
>
> The last command hangs after showing “Scanning dependencies of target
> test”.
>
>
>
> Environment:
>
>    - HPC with Rocky Linux 9.7
>    - PETSc version 3.25.3, compiled from source using cmake
>    - mpi implementation: Intel  2021.16
>    - compiler: fortran Intel 2025.2.0 ifx
>    - CMake version 3.31.6
>
> Other remarks:
>
>    - the problem did not occur when we still used an older version of
>    PETSc, version 3.22.4 (without any changes in environment and/or build
>    process)
>    - I can build the c version of the same file, ex16.c, without any
>    problems and delay
>    - the problem seems to occur only when a .h file that depends on
>    petscys.h is included in the fortran file (so also petscmath.h,
>    petscerror.h, petscviever.h, etc.)
>    - it seems that the process gets stuck in an endless loop while
>    scanning dependencies
>    - the actual fortran preprocessor:
>         ifx  -I[PETSC_INSTALL_DIR]/include -E ../ex16f.F90 > test.i
>    does not hang and completes immediately
>    - the problem does not occur for PETSC 3.22.4 but it does occur for
>    versions 3.24.6 and later
>    - with cmake 3.26.5 and 3.29.1 the problem also occurs
>
>
>
> Kind regards,
>
> Martijn de Ruyter de Wildt
> ​​​​
> dr.  Martijn  de Ruyter de Wildt  |  senior software engineer
> Research & Development  |  CFD Development
> T +31 317 49 35 60 <+31%20317%2049%2035%2060>  |  M +31 639 27 86 06
> <+31%20639%2027%2086%2006>   |  M.d.Ruyterd-Wildt at marin.nl  |
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